On Mon, May 18, 2015 at 8:41 AM, Ryan Pedela <rped...@datalanche.com> wrote:
> On Sun, May 17, 2015 at 9:41 PM, Josh Berkus <j...@agliodbs.com> wrote: > > Is there a particular reason why "+" makes more sense as "shallow >> concatination" and "||" makes more sense as "deep concatination"? Like, >> something in JS or other client languages which would make that >> preference make more sense to users? >> > > As someone who uses JSON day-to-day in Javascript and Python, I personally > don't think || or + matters much. Python uses json.loads() for JSON concat > and you have use a 3rd-party library in Javascript if you want that > functionality such as JQuery.extends(). I agree with Peter that we need > deep concatenation, but I don't think there is any standard for the > operator. I think the word "shallow" should be added to the docs though. > > What is far more important than shallow or deep concatenation for the > document database use case is being able to delete or replace/update a > specific, nested path in the JSON object. It looks like that is possible > with the minus operator and jsonb_replace(). This is great, however it took > me awhile to figure out the path syntax. I think adding a paragraph to the > docs explaining the path syntax would help. > Having looked at this more, I think I understand the problem Peter has identified and it is a significant usability problem in my opinion. I think the word "concatenate" has confused me because I think of it as a higher-level operation when I want to merge two, large JSON objects which isn't a very common operation, at least for me. What is absolutely required for the document database use case is the following: 1. Get element at any arbitrary path. ( #> operator ) 2. Delete any arbitrary path. ( minus operator ) 3. Replace/update element at any arbitrary path. ( jsonb_replace ) 4. Add element to any arbitrary path. ( ? ) It is #4 that does not seem to exist unless jsonb_replace() creates the specified path if it does not exist. Does it? I am not currently at my desk to test it myself. If not, deep concatenation would solve this problem, but I can also see another solution. Use + for shallow concatenation since it really means "add element to top-level path" as Peter suggests. Then add another function: jsonb_add( target jsonb, path text[], new jsonb ) to add element at any arbitrary path. Then leave || for deep concatenation in 9.6 or whenever. If jsonb_replace() satisfies #4 then I think everything is fine. Without #4 however, jsonb would remain an incomplete document database solution in my opinion. Thanks, Ryan Pedela
